Mitigative risk-reduction measures

Mitigative risk-reduction measures include system designs or procedures that help limit the magnitude or severity of an event. Examples are ... 

FN-curves and individual risk maps are useful tools for demonstrating the effects of a wide variety of risk reduction measures on fatality risks. They can thereby be used to facilitate the choice between alternative flood risk management strategies. Broadly speaking, there are three types of strategies to mitigate flood risks ... 

Adoption of the GALE principle means that if there are circumstances where the risk associated with a particular hazard increases, the system remains acceptable if it can be shown that risks in other areas have been reduced by an equivalent or greater amount. However, the principle does not remove the need to assess risk on a hazard by hazard basis or to seek to apply mitigation measures where reasonably practical. If a risk reduction measure can reasonably be put in place, even if it is not necessary to achieve the overall safety objective, the project is expected to consider applying this risk reduction. 

Seveik, A. Gudmestad, O.T.2014. Systematic Approach to Risk Reduction Measures in the Norwegian Offshore Oil and Gas Industry. Accepted for publication in 9th International Cenfererure on Risk Analysis and Hazard Mitigation, Wessex Institute, 4-6 June New Forest, UK. 

PHA is conducted in several steps (Echterling, 2011) including hazards detection, preliminary classification into risk categories, assessing mitigation or reduction measures and checks if the applied measures comply with the expectations. 

The HAZOP study was originally developed for the chemical process industry. The analysis team applies a set of so-called guidewords (like OTHER THAN or MORE ) to each combination of a process step (for instance a vessel) with a parameter (e.g. temperature) and analyses possible deviations fi-om design or process intent expressed by the combinations with respect to causes, consequences, and existing detection as well as risk mitigation measures finally, further risk reduction measures are recommended if necessary. 

Risk assessment The estimation of seismic risk is the fundamental step in risk management and decision-making for risk mitigation. Risk assessment refers to the probable future losses (physical, performance, economic, social) not only due to structural damages but also considering the business interruption or interdependencies of lifelines. Lifeline companies and civil protection authorities are asked to determine how to best allocate the limited resources for risk reduction measures (actions 2, 3, and 4) based on the results of seismic risk analyses for their facihties and the... 

Figure 4 illustrates the response and recovery time of a system with lower and higher resilience in relation with the risk reduction and readiness measures. Three cases are described with risk reduction and readiness measures (A), without risk reduction measures, but with readiness (B), and without any measures (C). Obviously, in reality there are several variations of risk mitigation measures, resilience levels, and recovery time. Ideally, in case A, the performance of the network can reach the pre-disaster... 

Blast resistant design, or the structural strengthening of buildings, is one of the measures an owner may employ to minimize the risk to people and facilities from the hazards of accidental explosions in a plant, Other mitigative or preventive measures, including siting (adequate spacing from potential explosion hazards) and hazard reduction (inventory and process controls, occupancy limitations, etc.), arc not covered in this report. 

The estimated impact is then compared to hazard acceptance criteria to determine whether the consequences are tolerable without additional loss prevention and mitigation measures. If the identified consequences are not tolerable, the next step is to estimate the ffequency/probability of occurrence of the identified failure modes leading to loss of containment. For simple cases, frequency estimates are combined with consequences to yield a qualitative estimate of risk. For complex cases, fault tree analysis is used to estimate the frequency of the event leading to the hazard. These estimates are then combined with the consequences to yield a measure of risk. The calculated risk level is compared to a risk acceptance criterion to determine if mitigation is required for further risk reduction. 

If risk reduction is required, prerelease mitigation measures are typically used first. If the risk is still not acceptable, postrelease mitigation is then used. Postrelease mitigation is less cost-effective than prerelease mitigation. 

Figure 7.24. Impact of alternate designs or mitigation measures on risk reduction (G. A. Melhem and P. A. Croce, 1994).

The outcome of the risk-based approach shown in Figure 7.23 is illustrated in Figure 7.24. The outcome can be either qualitative or quantitative. Figure 7.24 shows the impact of alternate designs or mitigation measure on risk reduction. A cost-effective solution is one where the risk is reduced to an acceptable level at a reasonable cost. 

As these parameters are monitored and changes in risk identified, critical issues can be escalated for more detailed review. Once several risk reduction strategies are identified, the same types of risk evaluation criteria (e.g., risk index, risk matrix, or other quantitative measures) described earlier in this book can be used to assess the relative benefits of each proposed risk mitigation option. Risk reduction can thus be defined as the process of evaluating and identifying options available to reduce risk, that achieve the desired level of risk reduction, and can be justified on a cost-benefit basis. 

In addition to the risk reduction benefits, the costs of risk mitigation options need to be evaluated. Due to the uncertainties associated with semi-quantitative and quantitative risk analysis results, a relative risk comparison, as compared to absolute measures of risk and benefits, is recommended. To conduct this type of relative comparison, incremental risk analysis can be used to evaluate the cost effectiveness of risk mitigation options, or determine the optimal combination of risk mitigation options. Figure 7.4 illustrates example results of this type of analysis, and uses the options from the F-N curve in Figure 7.3 as the basis for comparison. 

Estimate and compare cost effectiveness of each option, in terms of cost per unit risk reduction, keeping in mind a life cyxle perspective Rank risk control options on their cost effectiveness Estimate and compare cost effectivmess of each option, in terms espected benefit of vulnerabilirt reduction versus bnplememation cost, keeping in mind a life cycle perspective Rank vulnerability control options on their cost effectiveness Benefits of mitigating measures can also include benefits to normal operation (e.g increased fexibility). -Issess wfticA stakeholders pa and which would incur loss... 

The standard has both general and detailed requirements. General requirements include documentation of the system safety approach, identification of hazards, risk assessment, identification of risk mitigation measures, reduction of risk to an acceptable level, verification of risk reduction, review of hazards and acceptance of residual risk, and tracking of hazards and residual risk. When a government contract specifies MIL-STD-882D and no other requirement, only the general requirements apply. 

Radon—Requires the USEPA to withdraw its proposed radon standard and to set a new standard in 4 years, after NAS conducts a risk assessment and a study of risk-reduction benefits associated with various mitigation measures. Authorizes cost/benefit analysis for radon, taking into account the costs and benefits of indoor air radon control measures. States or water systems obtaiiving USEPA approval of a multimedia radon program in accordance with USEPA guidelines would only have to comply with a weaker "alternative maximum contaminant level" for radon that would be based on the contribution of outdoor radon to indoor air. 

Systematic failure normally occurs on account of design failure, including incorrect specifications, using a component not fit for the operation, and or due to error in software. Safety life cycle is adapted for systematic faults. So safety standards meant for E/E/PEs take care of both. SISs (Ref. Chapter VII) are developed to prevent or mitigate hazardous events to protect people or the environment, or prevent damage to process equipment. In this connection another important issue is SIL (Chapter VIII), which is a discrete level for specifying the safety integrity requirements of safety functions, but is not a measure of risk. SIL provides means for risk reduction to a tolerable level. The fundamental question, in case of functionally safe instrumentation, is how frequently failures of function will lead to accidents. The answers can be ... 

Nonetheless such a situation is not typical of India alone—many industrialized western European countries have encountered similar challenges in the past and evolved systematic methods for assessing risk from hazardous industries which then led to the adoption of suitable risk reduction strategies (Pasman and Reniers, 2013). In order to assess cumulative risk arising from a cluster of hazardous industrial establishments and to evaluate options for area level risk mitigation measures, few studies were carried out in countries like Netherlands, UK and Italy during the 1970 s. Some examples of these studies include those undertaken in Rijnmond, the Netherlands, Canvey Island in the UK and the Ravenna area in Italy etc. But then, it is only after the accidents in Bhopal... 

A safety measure is a special and intentional feature in the design of a system or product employed specifically for the purpose of eliminating or mitigating the risk presented by an identified hazard. A safety measure may not be necessary for system function, but it is necessary for safety (i.e., risk reduction). A safety measure can be any device, technique, method, or procedure incorporated into the design to specifically eliminate or reduce the risk factors comprising a hazard. 

In order to achieve fail operational behavioiu of the safety critical steering function, the Guidance System is developed by defining and managing adequate risk reduction strategies in terms of mitigating measures in system design and application conditions for each safety-related hazard such as ... 

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